If there is a definition of what makes an artisan I haven't seen it. I think of artisan as being a mom and pop outfit.
My experience is that there isn't that much difference in quality from the best artisans and the members of the Tier 1 group as specified in the first post of the popular thread by that name. I don't shave with hard water from a well and we all have somewhat different situations.
The way that I came to this conclusion is from experience with an exercise I call 'Face Off'. In this, I whip up lather with two different soaps or creams and shave half of my face with each. From doing this I have come to view soap or cream in one of two categories. Either I get a great close, comfortable shave or I throw it away.